The Bausch & Lomb Baltar 100mm f/2.3 is an American premium cinematography prime lens, manufactured in the 1970's It is designed for 6x6 cm frame. The copy reviewed here is likely to have been released in the late 60's - early 70's. The lens came in different modifications for different systems - later models have a different barrel design.
The Bausch & Lomb Baltar 100mm f/2.3 produces beautiful blurred foregrounds and backgrounds. It delivers good sharpness at already f/2.8. At f/2.3 the lens is moderately soft. There is visible fringing around bright subjects at f/2.3, at f/2.8 it vanishes. The lens is not resistant to back lighting. The diaphragm moves smoothly, which is suitable for shooting video. All in all, this is a splendid portrait lens.